1. Field of the Invention
Embodiments of the invention relate to DC-DC converters and, more particularly, to a multi-stage converter having a wide output voltage range and a control scheme to control operation of such converters.
2. Description of the Related Art
DC-DC converters are a class of power converter. They are used to convert a direct current (DC) signal from one voltage level to another. These converters are commonly used in electronic devices that are powered by regulated DC voltage. DC-DC converters are particularly useful in applications that have several different sub-systems, requiring several different voltage input levels.
DC-DC converters that use a magnetic energy storage mechanism employ inductors or transformers. The output voltage is controlled by modulating the duty cycle of the voltages used to charge the inductive component. Common types of magnetic storage DC-DC converters include buck and boost converters.
At least one challenge associated with boost and buck converters are reduced efficiency at high switching frequencies, as well as higher power loss. A typical arrangement for a DC-DC power switching converter is to use a cascaded unregulated full bridge and multiple post buck converters, as discussed in U.S. Pat. No. 7,072,190 to Schlecht. This type of converters cannot have a wide output voltage range because the key voltage rating of the power components is very high which results in a low efficiency.